Apparatus for recovering, reconditioning and reusing the used core sand employed in casting



K. MULLER 2,835,941 RING, RECONDITIONING AND REUSING Filed Oct. 9, 1956THE USED CORE SAND EMPLOYED IN CASTING May 27, 1958 APPARATUS FOR RECOVEINVENTOR Karl Mal/er United rates Patent APPARATUS FOR RECOVERING,RECONDITION ING AND REUSING THE USED CORE SAND EMPLOYED IN CASTING KarlMiiller, Koblenz-Metternich, Germany, assignor to Steinlein & Kunze G.in. b. H., Koblenz-Metternieh, Germany, a firm Application October 9,1956, Serial No. 614,927 Claims priority, application Germany April 18,1956 1 Claim. (Cl. 22--89) This invention relates to casting, and moreparticularly to an apparatus for recovering, reconditioning and reusingthe used core sand employed in casting.

As is known, a sand mold employed in foundry practice is useless after acasting has been made and is broken up and thrown on a rubbish heap. Inthis way the loss is very considerable in the course of time,particularly as regards the core sand as well as the binding materialand other valuable residues adhering thereto.

The object of the present invention is to provide an apparatus forrecovering these sand residues and the valuable components adheringthereto and to render them fit for further use after reconditioning themolding sand and particularly the core sand, in which the pieces of coresand are broken up in a rotary drum having an inner shell provided witha plurality of slots and an outer shell in spaced relation to said innershell and constructed as a sieve, with the aid of large metal balls,causing resultant sand grains to drop in continuous succession throughthe outer drum shell having a desired mesh width, removing by suction,during this operation, the dust from the drum and out of a sand catchingreceptacle, and periodically removing core pins and other solid residuesfrom the drum in known reverse movement.

The apparatus for carrying out this process comprises a rotary drumhaving an inner shell and an outer shell of diiferent diameters, anumber of thick metal balls in said inner drum shell, a hollow shaft onone side of the drum, a charging hopper extending from said hollowshaft, residue discharge means on the opposite side of the drum, theinner drum shell being provided with slots and the outer drum shellconstructed as a sieve with a mesh width determined by the grain size ofthe sand, a slotted funnel chute with a sand catching receptacleprovided underneath the drum, and exhausters arranged above said drumand on said slotted funnel chute.

By the frictional process in the inner, slotted drum shell the core sandparts fed therein are quickly broken up without the individual sandgrains being ground, and they drop immediately through the slots on tothe second, outer drum shell constructed as a sieve having a mesh widthcorresponding to the size of grain of the core sand being treated. Thesifted grains drop through the slotted funnel chute into the catchingreceptacle, the dust whirled up in the process being sucked off byexhausters.

According to another feature the valuable binding material and otherresidues adhering to the recovered sand grains are individuallyrecovered by suitable solvents and again used for preparing the moldingand core sand, for binding and stiffening the cleansed sand grains orthe initial material in question.

The invention enables the core sand pieces and the sand grains formingthese, to be fed in quick succession in pure condition and free fromdust for use again and, moreover, by the recovery of the bindingmaterial adhering to these sand grains, about 50% of the expensivetreatment material to be saved and rendered available for preparing thecore sand once more. For example, diluted water Patented May 27, 1958glass or other suitable chemicals, the cost of procuring which is in noproportion to the recovered expensive binding and stiffening agents, areused as solvents.

An apparatus for carrying out the process is illustrated by way ofexample in longitudinal section in the only figure of the accompanyingdrawing.

A rotary drum driven by a motor 1 consists of an inner drum shell 2provided with slots and a second, outer shell 3 mounted at a distancefrom the shell 2 and constructed as a sieve. The drum shell 2 is ofcylindrical cross section or flattened or constructed like a honeycomband accommodates several large metal balls 4. The material to beprepared, i. e. the core sand pieces, are fed by means of a lateralhopper 5 through a hollow shaft 6 into the drum. A slotted funnel-shapedchute 7 extends from the shell 3 underneath the drum and is connected upwith an exhauster, not shown in the drawing, for the purpose of drawingoff the dust produced. Similarly, an exhauster is connected to a shortpipe 8 mounted above the drum for removing the dust forming in the drum.

On the left side of the drum in the drawing there is a gap 9 between theface of the drum and its casing, which gap, through the intermediary ofsuitably arranged guide plates, communicates with a hollow shaft inwhich carries a conveyor worm 11. This arrangement serves for removingthe residues, such as core pins and the like, which remain on the sieveshell 3, and on this account the direction of rotation and the speed ofrotation of the machine is periodically changed by the motor with changeof pole connections, with the result that the said residues pass outthrough the hollow shaft 10.

The form of the apparatus described constitutes in eflect a preferredembodiment of the invention and it is to be understood that theinvention is not limited to this precise form of apparatus, and thatchanges may be made without departing from the scope of the inventionwhich is defined in the appended claim.

I claim:

In apparatus for recovering used core sand in its original granularstate, comprising a rotary drum including circumposed inner and outershells, a plurality of loosely disposed impact elements in said innershell insuflicient in number to grind the core sand disposed therein,means for introducing used sand cores axially of said inner shell, adischarge chute depending beneath said outer shell for conductingseparated core sand therefrom, said inner shell including a plurality oflongitudinally disposed slotted portions therethrough through which usedcore sand may pass and defining a friction surface on the innerperiphery of said inner shell, said slotted portions and impact elementsserving to only break up used sand cores, said outer shell comprising anannular sieve surrounding said inner shell and having a mesh size equalto the original grain size of the core sand being separated, saiddischarge chute including an intermediate bafiie portion for impedingthe fall of the separated core sand, and suction means communicatingperipherally of said outer shell and at the bafile portion of said chutefor drawing oif material mixed with the core sand of a size less thanthat of the separated core sand.

References Cited in the file of this patent UNITED STATES PATENTS

